1. Field of Invention
The invention relates to an electric drive apparatus, an electric drive control apparatus, and an electric drive control method.
2. Description of Related Art
In a related-art apparatus, an electric drive apparatus is mounted in an electric motor vehicle, which is an electric drive vehicle, so as to cause generation of torque of an electric motor that acts as an electric machine, that is, motor torque, and transfers the motor torque to driving wheels. The electric motor receives direct current from the battery, and is therefore driven to generate the motor torque during powering (driving). During regenerative operation (power generation), the electric motor receives torque due to the inertia of the electric motor vehicle, and therefore generates direct current and supplies the current to a battery.
Furthermore, in an electric drive apparatus which is mounted in a hybrid vehicle, as an electric drive vehicle, and in which an electric motor is coupled directly to a crankshaft of the engine, the electric motor is driven to start the engine, and the motor torque is transferred to the driving wheels.
Such an electric drive apparatus is equipped with, for example, an inverter for driving the electric motor, a motor control apparatus as an electric machine control apparatus, etc. When supplying current from a battery to the electric motor so as to drive the electric motor and therefore cause the electric motor vehicle or hybrid vehicle or the like to run, the motor control apparatus detects the position of the rotor of the electric motor, that is, the magnetic pole position, and generates a pulse width modulation signal corresponding to the magnetic pole position, and sends the pulse width modulation signal to the inverter, so that the inverter generates U-phase, V-phase and W-phase currents.
Normally, the detection of the magnetic pole position is accomplished through the use of an all-round embracing type resolver that is disposed on a shaft of the electric motor and embraces the entire shaft. However, if the resolver is disposed near the motor shaft, the size of the electric drive apparatus correspondingly increases.
Therefore, a low-resolution pulse generating type sensor is disposed near an outer peripheral surface of the rotor, and is used to detect the magnetic pole position. In this case, the detection of the magnetic pole position can be accomplished merely by disposing the sensor, so that the electric drive apparatus can be considerably reduced in size (see, for example, Japanese Patent Application Laid-Open Publication No. 2002-369570).